Incandescent lamp

ABSTRACT

In an incandescent lamp, particularly projection lamps of large luminosity, both ends of an upper glass bar for holding down supporting hooks, which hangingly support segmented coils of an incandescent filament, are welded to specified positions on the inner face of the bulb, so as to secure the filament rigidly and durably.

United States Patent 1 in] 3,8 Nakamura [45] Apr. 1, 1975 [5INCANDESCENT LAMP 3.244.926 4/1966 Eyer et al. 313/252 x 3.440.4734/1969 Smith et al 3l3/273 X [75] Takes Japan 3.496.403 2/1970 Palermoet al 313/273 x Assignee: Matsushita Electronics Corporaion, PctcrSOn XKadoma. Osaka Prefecture. FOREIGN PATENTS OR APPLICATIONS 35.4rs 1/1953Poland 313/252 [22] Filed: Nov. 13, 1973 P b Alf d E S h v rimary'xaminerre mit [211 App! 5 Assistant Examiner-Saxfleld Chatmon. .lr.

' Attorney. Agent, or Firm-Craig & Antonelli [52] US. Cl 3l3/274.3l3/273. 3l3/275.

3 3 277 [57] ABSTRACT [51] int. Cl HOij l/96, HOij 19/50 in anincandescent lamp. particularly projection lamps [58] Field of Search313/273, 274, 275, 276. of large luminosity, both ends of an upper glassbar for -3l3/277, 278 holding down supporting hooks, which hangingiysupport segmented coils of an incandescent filament, are [56] ReferencesCited welded to specified positions on the inner face of the UMTEDSTATES PATENTS bulb, so as to secure the filament rigidly and durably.960.962 6/1910 Kuzel 313/277 X 4 Claims, 4 Drawing Figures INCANDESCENTLAMB BACKGROUND OF THE INVENTION This invention relates to anincandescent lamp, in particular to the supporting (propping)construction of its filament. Among such incandescent lamps. thisinvention concerns those for spot lighting or narrow beam projecting.especiallylamps of large luminosity.

For the incandescent lamp. it is very important. needless to say. thatits incandescent filament must be rigidly and securely supported in itsbulb. Sucha requirement is especially keen fora lamp which is designedfor t a spotlighting. i.e.. for narrow beam projecting purposes.

lating bars bridging said leadin wires at their top ends and stem parts.respectively. Also. a specified number of supporting hooks are provided.each having one end embedded and fixed in said upper insulatingbar andthe other hooked endhangingly holding the filament coils, in such aconstruction. however. for lamps of larger output and higher power. thefilament must have an increasingly greater size and weight. and hence.it is necessary to proportionatelyenlarge the diameter of the twolead-in wires in order to prop the filament rigidly in the rightposition. Such enlarging of the diameter consequently invites mechanicaland thermal weakening of the parts where said lead-in wires contact theinner glass face of the bulb. thereby hampering the manufacturingprocess. t

SUMMARY OF THE INVENTION struction wherein emission from the filament isnot interrupted by the lead-in wires. i

A further object of this invention is to provide incandescent lamps ofthe above-described kinds embodying greater freedom'in designing assmall a means as possible for propping the filament inside the bulb.thereby making it possible to reduce the size of the bulbs.

In order to attain such objects as mentioned above. the presentinvention is characterized by fixing the upper insulating bar to theinner face of a bulb by welding. namely by heating. melting andthenconnecting. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspectiveview of a halogen projection lamp embodying the present invention; a

FIG. 2a is a front view partially in section of a halogen projectionlamp embodying the present invention;

FIG. 2b is a side view partially in section of the lamp in H6. 2a; and

FIG. 3 is an exploded perspective view showing com ponent parts ofahalogen projection lamp embodying the present invention. for thepurpose of explaining one method of theprocess of assembling the same. i

DETAILED DESCRlPTlON OF THE lNVENTlON FIG. 1 shows a halogen projectionlamp. embodying the present invention. In FIG. 1 an enclosure 1 made ofquartz glass encloses an incandescent filament 2. a

Moreover..the lead-in wires 3can be short and their. a upper ends needonly hold the lower ends of the segf mented coils propped by the upperglass bar 7. Therepair of lead-in wires 3, and a filament supportingmeans 4.The enclosure 1 has a cylindrically shaped trunk portion whichextends through a tapered part 21 and ends in a pair of tubes 6. Theenclosure 1 further encloses amixture of argon gas and a specifiedquantity ofmethylene bromide and hydrogen bromide.

The filament 2 is made of a tungsten wire and formed into six segmentedcoils 5 which are arranged in a zigzag row on a level plane in such amanner'that the axes of the coils are disposed substantially inparallel. The

pair of |ead-in wires 3. which feedsthe current in the quartz glass bar7 disposed at right angles to the axis of the bulb and three supportinghooks 8 made of tungsten wires. one end of eachbeing embedded in andfixed to said upper glass bar 7. Both ends 9 and 9 of said upper glassbar 7 are welded on the inner face of the enclosure 1. The other ends ofsaid supporting hooks 8 are bent up to hang'down and engage upperspacers 10 which are the noncoiled parts formed between the segmentedcoils 5. The coils are also secured underneath at lower spacers by lowersupporting hooks 15. The ends 11 and 11' of the filament 2 are windinglyconnected to respective ends of linking wires 13 which 1.

are in turn wound on the respective lead-in wires 3 near their upperends 12. The other ends of thelinking wires 13 are respectively fastenedto a lower quartz glass bar 14, into which said lower supporting hooksl5 of tungsten wires are fixed. The lower supporting hookslS A pull downthe lower spacers of the filament 2. The pair, of lead-in wires 3 neednot be extended all the way along the filament assembly up to the upperglass bar as in the conventional projection lamp. but the lead-in wires3 terminate slightly below the lower ends of the segmented coils 5.

As describedabove.the upward propping of the fila- L ment 2 isaccomplished by the upper glass bar 7 firmly fixed to the upper portionof the inner face of the enclosure 1. Hence. the construction is veryrigid and se cure. as well as strong against vibrations and shocks.

fore. the lead-in wires 3 dispense with the need of the conventionalconstruction to rigidly support the heavy weight of filament. etc.. bylong wires passing beside the filament. Accordingly. the lead-inwirescan be much finer and shorter. and hence. the work required plified.FIG. 2 shows a for passing the lead-in wires 3 into the bulb can besimsecond example of the invention. In

FIG. 2 most of the parts are constructed in a similar 3 segmented coils16 at both sides. namely. both ends of the filament coils 2 are formedas connecting coils l7 wound around and connected to the upper ends ofthe lead-in wires 3. A lower glass bar 14 is fixed to the mid dle partof the lead-in wires 3 which penetrate the glass bar 14. Theglass bar 14has supporting books 15 supporting lower spacers 10' of the filament 2.The parts of the lead-in wires 3 embedded in the lower glass bar 14 areslightly bent or have rugged surfaces in order to be firmly fixed. Abase 18 is fixed to the stem part.

An actual example of the embodiment of FIG. 2, a.

halogen lamp of BKW/ 100V performance is as follows:

the diameter of the enclosure is 45 mm. and the length from the top tothe bottom face of the base is 200 mm. The filament consists of six coilsegments. each being wound for 26.5 turns of [.6 mm inner diameter and 1mm pitch with 0.665 mm tungsten wire. The spacers length. The segmentsof the coilsare so arranged that.

the distance between the axes of the segments on both extreme sides(i.e.. the? axes of both outermost segments) is 25 mm. The upper andlower glass bars 7 and 14 are of roughly 6mm diameter and the supportinghooks 8 and 15 are of 0.7 mm diameter tungsten wire. The end spacers111. may be connected to the upper ends of the lead-in wires 3 byplacing their ends to ends contacting each other and continuouslycovered by connecting coils.

As a result of the above-mentioned construction. the lamp of the secondexamplehas the following advantages besides the advantages of the firstexample.

Since the upperends of the lead+in wires 3 are situ- 7 I ated coaxiallywith the segment coils 16 of the extreme sides of filament 2.thedistance between the two leadin wires 3 can be made very short. andconsequently. the diameter of the enclosurecanbe made small. This endsof which are airtightly secured to the leading-in wires 3. The taperedpart 21 is a short glass cylinder having an upper open end to beconnected to the lower open end of the bulb 19. the upper open 'end ofthe tapered tube having a diameter just to fit inside the lower open endof the tube. The tapered part has two lower openings to be connected tothe upper ends of the tubes 6, the lower openings having a diameter tofit out:

side the upper ends of the tubes 6.

The first step of assembling the lamp is to secure the upper glass bar 7at a suitable location in the upper part ofthe bulb 19. The securing ismade by holding the glass bar 7by ajig at a suitable position andheating the surface of the bulb at the position to be welded (melted andsecured) by gas flames. and then by pressing the half-melted part of thebulb wall toward the ends of the glass bar 7.

The second step is to insert the filament assembly 20 it into the bulband hang the spacers between segmented coils 5 of the filament 2 on thesupporting books 8. Y

The third step is to cover the tubes 6 and filament assembly with thetapered part 21, and. to-seal the lower opening of the bulb l9 and theupper opening of the tapered part 21. and to seal the lower openings ofthe tapered part 21 and the upper part of the tubes 6. The sealings aremade by heating and welding the parts to unite them to each other. i

The fourth step is to evacuatethe sealed bulb. injecting argon gascontaining a specified small amount of methylene bromide, and sealingtheevacuation tube 22 by heating and pinching.

When desired, a base 18 is secured at the lower end i While I have shownand described several embodiments in accordancewith the presentinvention. it is understood that the same is not limited thereto but issusceptible of numerous changesand modifications as known to a personskilled in the art.'and l therefore do i not wish to be limited to thedetailsshow n and deis very advantageous as the halogen lamp in whichthe shielded or absorbedby the lead-in wires supporting thefilament.-and can enjoy the resultant advantage of high efficiency ofconversion.

electric power to luminous output The process of assembling or makingthe abovementioned lamps will be explained below with reference to FIG.3. As shown in FIG. 3. which isan exploded perspective view of the lampof FIG. 2. abulb 19. a glass bar I having several supporting hooks 8, afilament assembly 20 and a tapered part 21 are provided. The bulb 19 ina glass cylinder with an evacuation tube 22 at the top and with a broadlower opening. The upper glass bar7 is made by the process of at first,holding the fixed ends of the supporting hooks 8 between a pair of glassbars. and then heating and pressing the glass bar so that the two glassbars are united into one glass bar with the ends of the supporting hooks8 embedded therein. The filament assembly comprises the filament 2, apair of the lead-in wires 3, the glass bar 14 supported by the lead-inwires 3, the lower supporting hooks l5 fixed to the glass bar 14. and apair of glass tubes 6, the lower scribed herein but intend to cover allsuch changes and modifications as are obvious to one of ordinary skillin What isclaimedis; t p 1. An incandesce'nt lampcomprising aglassenclosure, i an incandescent filament enclosed in said glassenclosure. a pair of leadin wires extending through said glassenclosurefor feeding electricalcurrent to said filament. an upperglassbar having its ends welded to the innerface of said glass enclosure atone end thereof. a L

lower glass bar being secured in position within said "glass enclosureat the other end thereof while having its.

ends left free from said glass enclosure. and supporting hooks extendingbetween said upper glass bar and said filament and between said lowerglass bar and said filamentfor supporting said filament in a desiredposition. 2.. An incandescent lamp as defined in claim 1 wherein theupper ends of said lead-in wires terminate below said filament.

3. An incandescent lamp defined inclaim. 2w

wherein said filament is formed into several segmented coils havingtheir axes substantially parallel to the lamp axis. and the upperends ofsaidlead-in wires being situated coaxially with the outermost segmentedcoils of the filament.

4. An incandescent lamp as definedflin claim 3 wherein said lower glassbar is fixed by saidpair of leadin wires penetrating therethrough. 7

e t e s t:

1. An incandescent lamp comprising a glass enclosure, an incandescentfilament enclosed in said glass enclosure, a pair of leadin wiresextending through said glass enclosure for feeding electrical current tosaid filament, an upper glass bar having its ends welded to the innerface of said glass enclosure at one end thereof, a lower glass bar beingsecured in position within said glass enclosure at the other end thereofwhile having its ends left free from said glass enclosure, andsupporting hooks extending between said upper glass bar and saidfilament and between said lower glass bar and said filament forsupporting said filament in a desired position.
 2. An incandescent lampas defined in claim 1 wherein the upper ends of said lead-in wiresterminate below said filament.
 3. An incandescent lamp as defined inclaim 2 wherein said filament is formed into several segmented coilshaving their axes substantially parallel to the lamp axis, and the upperends of said lead-in wires being situated coaxially with the outermostsegmented coils of the filament.
 4. An incandescent lamp as defined inclaim 3 wherein said lower glass bar is fixed by said pair of lead-inwires penetrating therethrough.